Uhh... Mo isn't even wearing the earring in this chapter.
Think it's near his house. In the previous chapter he was already looking for him so it makes sense he'll be near his house. The earring thing doesn't make sense since 1. as you say he's not wearing it 2. It's kinda a wacky theory. The guys bullying Mo mention a debt so probably his dad did owe money or something and now they are pushing it on the mom and Mo since the dad is in jail. They probably know where they live. It makes sense why Mo is desperate for money now. To pay off the debt so his mom is safe.
I just realized I repeated myself too much (sense, sense, sense) but hopefully this was still helpful to someone
It was probably really near Mo's house.
And that's guys wanted money from his mother that they probably colect from time to time...some kind of extortion,has smt to do with his dad and the whole thing why he is in jail.
Yes, this isn't something unfamiliar. It's not hard to make that connection. The problem, I feel, is that there wasn't any event before that led up to this particular interaction, and thus it feels a bit out of nowhere. An excuse to create a scenario where Mo is fighting and is saved by He Tian. Although actually there's not much of an excuse here, the whole thing just kinda... happens, and this is my problem with this.
Have I missed something? It feels like there's no context here. Why is he there talking to them all of a sudden, and how did He Tian know he was there? It alls feels a little out of nowhere.